package shy;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        char[] ch = in.next().toCharArray();
        long s = 0, sh = 0, res = 0;
        for (int i = 0; i < n; i++) {
            if (ch[i] == 's') {
                s++;
            } else if (ch[i] == 'h') {
                sh += s;
            } else if (ch[i] == 'y') {
                res += sh;
            }
        }
        System.out.println(res);
    }
}